Underwater completion system

ABSTRACT

The guide base installed as an initial step in drilling an underwater well includes an upwardly opening generally hemispherical shell. Later, during christmas tree installation or work-over operations a man-carrying chamber is lowered to mate with the shell. Sealing between the chamber and the shell is accomplished using axially spaced inflatable toric circumferential seal elements carried exteriorly of the lower end of the chamber and expansible into sealing contact with the shell.

llnited States Patent Holbert, Jr. et al.

[151' 3,656,549 51 Apr. 18, 1972 dress, both of Houston, Tex.

[73] Assignee: Gray Tool Company, Houston, Tex.

[22] Filed: Sept. 17, 1969 211 Appl. No.: 858,765

[52] US. Cl ,.166/.5, 61/69 [51] Int. Cl ..E2lb 43/01 [58] FieldofSearch ..l66/.5,.6; 175/5,6, 8,9; 61/69, 46.5

[56] References Cited UNITED STATES PATENTS 2,854,215 9/1930 Cox..166/.5 2,988,144 6/1961 Conrad ..166/.5

3,361,199 1/1968 Haeber et al. ,.l66/.5 3,408,822 11/1968 Chate et a1....6 l /69 3,482,410 12/1969 Roesky et a1 ..166/.5 X 3,504,740 4/1970Manning 166/ .5 3,513,910 5/1970 Townsend ..166/.5 3,525,388 7/1970McClintock ..61/46.5 X

Primary Examiner-Marvin A. Champion 7 Assistant Examiner-Richard E.Favreau Attorney-Cushman, Darby & Cushman [5 7] ABSTRACT The guide baseinstalled as an initial step in drilling an underwater well includes anupwardly opening generally hemispherical shell. Later, during christmastree installation or work-over operations a man-carrying chamber islowered to mate with the shell. Sealing between the chamber and theshell is accomplished using axially spaced inflatable toriccircumferential seal elements carried exteriorly of the lower end of3,020,956 2/1962 sudel'ow the chamber and expansible into sealingcontact with the shell. 3,202,218 8/1965 Watts 612 a1 ..166/.5 3,353,36411/1967 Blanding et al. ..166/.5 3 Claims, 12 Drawing Figures 44 l 2 #46H l '11 PATENTEDAPR 18 m2 3.656549 22 /vy v 56 v INVENTORS 74 F A fiazageg Jig ATTOR N E Y5 PATENTEDA R 18 m2 3, 656,549

- I NVENTORS flew/VJ 174165641 5 ATTORNEYS PATENTEDAPR 18 I972 8 656,549

SHEET as @s' g INVENTORS Mdw/Vfdb/lpgfss MMQ ATTORNEYS PATENTEDAPRW I9723,655,549

swear w a? 2*,

ATTORNEY;

UNDERWATER COMPLETION SYSTEM BACKGROUND OF THE INVENTION In the courseof drilling and completing oil and gas wells, a means of gathering andtransporting production to a storage and/or delivery point is usuallyrequired.

As the drilling operation and the laying of production pipe lines (flowlines) are necessarily conducted as separate operations, the finalconnection between wellhead and flow line (and the storage facility, ifsubmerged), has historically presented problems of considerablemagnitude.

The normal solution has been the use of divers and seems effective wheredepths are not excessive, visibility good and water temperatures notunbearably low.

However, in view of recently proposed deep water drilling concepts, theuse of divers and equipment considered operational and efficient atdepths less than 300 feet is not desirable when considered at 300 to1,000 feet.

In an effort to circumvent the limitation imposed by these deep wateractivities, attempts have been made to automate flow line connectionoperations so that they may be carried out remotely.

The remote equipment thus far developed is quite complex and necessarilyexpensive. In addition, the obvious possibility of damage andmalfunction in such an inaccessible location could result in loss ofproduction and water pollution.

Examples of remote flow line connection systems known to the presentinventors are shown in the following United States patents:

Inventor Patent No. Issue Date Haeber 2,965,174 Dec. 20, I960 Knapp etal. 2,970,646 Feb. 7, I961 Geer et al. 3,052,299 Sept. 4, I962 Watkins3,166,123 Jan. 19,1965 Geer et al. 3,233,666 Feb. 8, 1966 Shatto, .Ir.3,299,950 Jan. 24, 1967 Shane, Jr. 3,307,627 Mar. 7, I967 Haeber et al.3,361,199 Jan. 2,1968

Similar problems are encountered in other underwater well completion andwork-over operations.

Others have proposed the use of man and equipment carrying submersiblechambers for use in the completion of wells or for working upon wells.Examples of which the present inventors are aware are shown in thefollowing United States patents.

The provision of a work chamber which includes a fixed lower portion andan upper portion which may be lowered, latched and sealed to the portionso that workers may complete the well in an air-filled, atmosphericpressure caisson is illustrated in the 1961 U.S. patent of Conrad, U.S.Pat. No. 2,988,144. In this patent, the latches provided are of thecable actuated, swinging dog type 60, 90; the seals 63, 38 are of anoninflated, rubber type; and the flow line connection at 86 isdescribed as being made-up using divers or other caisson equipment (notfurther explained), column 5, lines 36-42.

In the general context of the present invention, two axially spaced,although noninflated, seals were provided in Watts et al., U.S. Pat.Nos. 3,202,216 and 3,202,217. FIG. 11 of the fonner shows communicationprovided at 173 to the space between the seals for venting and plasticpacking material injection. In Watts et al., U.S. Pat. No. 3,202,216 ahydraulic piston-type latch is provided at 100' in FIG. 11.

In the expired U. S. patent of Ferro, U.S. Pat. No. 2,303,831 anoninflated rubber seal is shown at 31, 32 (FIG. 2) between a base(submarine) and a chamber (escape bell).

Getting such sealing areas to slide past one another to their intendedsealed relationship can be difficult because of the close tolerancesinvolved.

Inflatable seals for connecting lowerable working chambers to guidebases or fixed chamber floor elements are shown at 31 in FIG. 2 ofSuderow, U.S. Pat. No. 3,020,956 and at 439 in FIG. 18 of Blanding etal., U.S. Pat. No. 3,353,364. The Suderow patent mentions that its sealsare similar to those shown in Pointer, U.S. Pat. No. 2,775,869.

, 2 SUMMARY OF THE INVENTION The present invention relates to anunderwater completion system utilizing a submersible work chamber whichseals with a permanent hemispherical shell at the wellhead viainflatable seals which are positively actuated and allow a largeclearance to be provided between the shell and the work chamber.

When using the apparatus of the invention, personnel may performconventional oil field operations at sub-sea" locations in an acceptableenvironment with respect to normal breathing and temperature conditions.This, of course, would eliminate the need for auxiliary breathingapparatus, diving suits and time consuming decompression procedures.Although the immediate use of this system is discussed in terms 0 oilfield operations, this certainly is not intended to be a limitation ofits use in sub-sea (including sub-aquatic) environments including usewith underwater vessels, undersea resource exploration and extractionequipment, diving bells and escape devices.

Briefly, the submersible chamber carrying specialists trained in theefficient manipulation of, in this case, oil field equipment, may belowered and attached to a permanently located receptacle. Followingthis, the juncture is sealed and the sea water removed from the enclosedspace. This evacuated chamber, charged with a breathable gas mixture,can then be safely entered by the specialists and all manner ofoperations performed in an accommodating atmosphere.

It should be appreciated that when the work chamber is attached to thelower hemisphere, adequate means must be provided for sealing thejuncture, to the exclusion of sea water. In addition, the seal mustwithstand full hydrostatic differential between the enclosed work areaand the external pressure of sea water once the work area has beenpurged of sea water and the internal pressure reduced to l atmosphere(approximately). In addition, inevitable marine growth and other foulingwould present very hostile conditions on permanently submerged sealingsurfaces.

As rather large annular clearances are highly desirable between the workchamber and the lower hemisphere to facilitate their assembly anddisassembly, the present inven. tion provides inflatable type seals.These seals are carried on the chamber for sealing against thehemispherical shell.

Once the chamber is in place, hydraulic fluid under pressure is injectedinto the seal elements, causing them to expand, contacting the innersurfaces of the hemispherical shell. The inflating pressure thusentrapped provides a leak-proof barrier between the work chamber and seawater.

Preferably, two axially spaced seals are provided. The purpose of twoseparate seal elements is threefold: (l) for the safety factor of asecondary seal, (2) the void between the two elements can be monitoredto prove the integrity of the primary seal-also, this cavity can beexhausted through use of a pump, relieving the secondary seal ofunnecessary stress until such time it may be required, (3) a thirdbenefit of the dual seal system is that of permitting the passage ofhydraulic power from the work chamber of the upper member which can beutilized to operate valves or other equipment which may have beenpermanently installed in the lower hemispherical shell.

For several years, the petroleum industry has recognized the fact thatas the search for petroleum extended into the deeper waters of thecontinental shelves, there would be a water depth eventually reachedwhere the cost of conventional and accepted means of depleting an oilreservoir via fixed platforms would be economically prohibitive. It wasfurther recognized that any technological breakthrough in this regardwould probably entail development of the tools and techniques wherebythe wells could be completed, produced and serviced on the ocean floorthereby circumventing the need for fixed platforms which becomeextremely expensive in deeper waters.

The system disclosed herein may be utilized as an integral part of aprogram for depleting oil from an offshore petroleum reservoir in waterdepths of from about up to about 1,000

feet, by drilling, completing, producing and servicing a plurality ofwells from the ocean floor. n so doing, wells may be drilled with afloating rig or mobile bottom supported units in certain conditions, andcompleted on the ocean floor with the base structure, in the form of aface-up hemispherical shell, being an integral part of the wellheadassembly and encompassing the christmas tree. This hemispherical basestructure will have a top connection that will be compatible with adiving bell or work chamber which will be logistically supported by abell tender on the ocean surface. This diving bell will transport menand tools, in a l-atmosphere environment, from the bell tender to anyparticular well where a water-tight seal will be effected between thebell and the wellhead hemisphere. The trapped water will then beexpelled, thereby exposing the wellhead, so that operations such asinstallation and maintenance of christmas trees and wellhead separators,installation and connection of flow lines, service work, pressuresurveys, and other wireline work can be performed.

Each individual well may be equipped with a wellhead separator whichwill be utilized to separate most of the gas from the oil; the gas maybe vented to the ocean if uneconomical to gather and the oil may berouted into a submarine pipeline system which does not form a part ofthe present invention. Such a submarine pipeline system may connect thewells with a central gathering manifold resting on the ocean floor neara monobuoy mooring complex. The oil can be routed through flexiblepiping from the central manifold up through the monobouy and then onto amoored, floating storage vessel for further processing, storage andeventual trans-shipment to shore.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a longitudinal vertical sectional view of a partly completedunderwater well at a first stage thereof showing the primary landingbase in place;

FIG. 2 is a longitudinal vertical sectional view of a partly completedunderwater well at a second succeeding stage thereof, showing thewellhead hemisphere in its last few feet of descent;

FIG. 3 is a longitudinal vertical sectional view of a partly completedunderwater well at a third stage thereof showing drilling operationswith mud returns diverted over the side of the wellhead hemisphere;

FIG. 4 is a longitudinal vertical sectional view of a partly completedunderwater well at a fourth stage thereof showing drilling for receiptof the next inner string of casing, through a blowout preventor (B.O.P.)stack;

FIG. 5 is a longitudinal vertical sectional view of a partly completedunderwater well at a fifth stage thereof showing further drillingoperations conducted through a narrower bore blowout preventor stack;

FIG. 6 is a longitudinal vertical sectional view of a partly completedunderwater well at a sixth stage thereof showing all casing and tubinghung and locked in place and/or cemented and the wellhead hemisphereready for receipt of the work chamber;

FIG. 7 is a side elevation view of the work chamber with parts insection to expose detail, showing connection with the wellheadhemisphere for installation of production flow lines, the conducting oftests and related completion and servicing activities;

FIG. 8 is a top plan view of the underwater work chamber;

FIG. 9 is a side elevation view of the underwater work chamber;

FIG. 10 is a fragmentary longitudinal vertical sectional view of anunderwater well showing the submersible underwater work chamber latchedin place with the seals inflated and production flow line equipmentinstalled on the well;

FIG. 11 is a fragmentary longitudinal vertical sectional view, on anexpanded scale, of the seal and latch area of the hemispherical shelland upper work chamber;

FIG. 11A is a fragmentary radial horizontal sectional view substantiallyalong the line AA of FIG. 11'; and

FIG. 12 is a perspective view of the upper work chamber leaving afterconducting completion, servicing or work-over operations on anunderwater well which is one of several in an underwater field, eachwell being permanently equipped with a wellhead hemisphere.

The principles of the invention will be further hereinafter discussedwith reference to the drawings wherein a preferred embodiment is shown.The specifics illustrated in the drawings are intended to exemplify,rather than limit, aspects of the invention as defined in the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT The following is a descriptionof a typical well drilling, and completion, by stages, utilizing thehemispherical shell, wellhead hemisphere" and the submersible workchamber of the invention. In the following description, the particularcasing program, dimensions and the designation of apparatus ofparticular manufacturers are exemplary.

THE DRILL SHIP IS POSITIONED OVER PREDETER- MINED LOCATION. IFCONSIDERED NECESSARY, OCEAN FLOOR 10 (FIG. 1) COULD BE CHECKED FORSUITABILITY OF RECEIVING THE PRIMARY BASE 12.

STAGE I A. MAKE UP J TOOL 14 ON DRILL PIPE 16 AND JAY INTO PRIMARY BASEUNDER THE ROTARY.

B. FILL PRIMARY BASE WITH CEMENT 17 AND/OR WEIGHT ED MATERIAL SO IT WILLHOLD ITS POSI- TION ON BOTTOM.

C. ATTACH GUIDE LINES 18 TO BASE.

D. LOWER PRIMARY BASE TO OCEAN FLOOR ON DRILL PIPE.

E. DISENGAGE .l" TOOL 14 FROM BASE BY TURN- ING DRILL PIPE 16 TO RIGHT.DRILL PIPE TO SUR- FACE.

F. RIG GUIDE LINES 18 TO TENSION WINCHES.

STAGE II A. MAKE UP PILOT BIT ON DRILL STRING.

B. INSTALL GUIDE FRAME, COMPLETE WITH DRILL STRING ADAPTER, ON GUIDELINES.

C. LOWER DRILL STRING AND GUIDE FRAME, TO ENTER DRILL BIT THROUGHOPENING 19 IN PRIMARY BASE 12.

D. DRILL PILOT HOLE WITH RETURNS ONTO THE OCEAN FLOOR.

E. PULL DRILL STRING AND GUIDE FRAME.

F. PICK UP 36INCI-I HOLE OPENER, INSTALL GUIDE FRAME AND COMPLETECONDUCTOR HOLE.

G. PICK UP AND TIE OFF THE CELLAR BASE 20 (FIG. 2) BELOW THE ROTARY;(MOON POOL OR SECOND DECK).

H. PICK UP BOTTOM SECTION OF CONDUCTOR PIPE 22 AND STAB THROUGH CELLARBASE 20 (LOWER, UPWARDLY OPEN, HEMISPHERICAL SHELL BASE). INSTALL GUIDEFRAME, COMPLETE WITH CONDUC- TOR ADAPTER, ON GUIDE LINES. ATTACHRETRIEV- ING CABLE TO GUIDE FRAME. LOWER BOTTOM OF CONDUCTOR THROUGHPRIMARY BASE TO A POINT THAT WILL PRECLUDE ITS PULLED OUT WHEN MAK- INGA CONNECTION; THEN RETRIEVE GUIDE FRAME.

I. LOWER CONDUCTOR PIPE UNTIL THE 30 INCH HOUSING 24 HUB 26 REACHES THECELLAR BASE. IN- STALL GRAYLOC CLAMP 28 AND TEST CONNECTION THROUGH TESTPORT. WITH THE RUNNING TOOL 30 ATTACHED TO THE CONDUCTOR HOUSING 32, THECELLAR BASE AND CONDUCTOR PIPE ARE LOWERED TO THE SEAT 34 ON THE PRIMARYBASE 12.

.I. CEMENT 36 CONDUCTOR PIPE THROUGH DRILL PIPE. EXCESS CEMENT RETURNSTO OCEAN FLOOR AND PRIMARY BASE BENEATH THE CELLAR BASE.

K. WHEN PRESSURE CAN BE RELEASED, TURN DRILL STRING SIX TURNS TO RIGHTTO RELEASE RUNNING TOOL AND PULL TO SURFACE. NOTE:

IF WATER DEPTH IS SUCH THAT BOTTOM OF CON- DUCTOR PIPE HAS NOT ENTEREDPRIMARY BASE BE- FORE THE INCH HOUSING AND CELLAR BASE IS ATTACHED TOTHE TOP END OF THE CONDUCTOR PIPE; THEN A BREAK-AWAY GUIDE FRAME CAN BEUSED THAT IS RELEASED BY TRIPPING A LATCH. ALSO, THE TWO GUIDE LINES 18FROM THE PRIMARY BASE MAY BE RETRIEVED BY SHEARING THE PINS.

THE CELLAR BASE 20 HAS CARRIED DOWN WITH IT THE FOUR GUIDE POSTS 38 ANDGUIDE LINES 40 THAT ARE TO BE USED FOR THE POSITIONING OF BLOWOUTPREVENTER STACKS THAT WILL BE USED IN FUTURE DRILLING OPERATIONS. TWOADDI- TIONAL GUIDE LINES ARE PROVIDED IN THE EVENT T.V. CAMERAS AREUSED.

STAGE III WHILE DRILLING HOLE FOR, RUNNING AND CE- MENTING 20 INCHCASING; IT WILL BE NECESSARY TO KEEP MUD, CUTTINGS AND CEMENT FROMGETTING INTO THE CELLAR BASE. THEREFORE, WE EMPLOY A 30 INCH HYDRIL MUDDIVERTER 42 (FIG. 3) AND AN OVERFLOW NIPPLE 44 BELOW IT TO PUT THERETURNS 46 OVER THE SIDE.

A. THE MUD DIVERTER, WITH A CONNECTOR 48 FOR ATTACHING TO THE 30 INCHCONDUCTOR HOUSING 32 IS SWUNG INTO POSITION BENEATH THE ROTARY.

B. THE GUIDE FRAME, WITH ADAPTER 50 TO FIT DIVERTER IS ATTACHED TO GUIDELINES 40.

C. WITH THE RUNNING TOOL AND DRILL STRING ATTACHED, THE DIVERTER 42 ISLOWERED AND FASTENED TO THE CONDUCTOR HOUSING 32.

D. TURN DRILL STRING 6 TURNS TO RIGHT TO RELEASE RUNNING TOOL.

E. PULL TO SURFACE, INSTALL 26 INCH BIT 52 ON DRILL STRING 54.

F. INSTALL GUIDE FRAME WITH DRILL STRING ADAPTER TO GUIDE LINES.

G. LOWER DRILL 54 STRING UNTIL 26 INCH BIT 52 HAS ENTERED CONDUCTOR PIPE22.

' H. ACTUATE PRESSURE TO CLOSE DIVERTER 42 ON DRILL STRING 54'.

I. CONTINUE TO BOTTOM AND DRILL 26 INCH HOLE.

J. WHEN HOLE IS COMPLETED, PULL BIT 52 UP TO DIVERTER 42. RELEASEPRESSURE TO OPEN DIVERTER 42 AND PULL DRILL STRING 54 TO SUR- FACE.

K. PICK UP BOTTOM SECTION OF 20 INCH CASING 56 (FIG. 4). INSTALL GUIDEFRAME 58 WITH ADAPTER TO 20 INCH CASING.

L. ATTACH RETRIEVING CABLE 60 TO GUIDE FRAME.

M. MAKE UP REMAINDER OF 20 INCH CASING AND ATTACH RUNNING TOOL AND DRILLSTRING. LOWER 20 INCH CASING TO BOTTOM.

N. UNLATCH GUIDE FRAME AND PULL TO SUR- FACE.

O. CLOSEDIVERTER AND CEMENT THE 20 INCH CASING. RETURNS GOING OUTSIDE OFCELLAR BASE.

P. INSTALL DRILL STRING ADAPTER TO GUIDE FRAME AND LOWER TO BOTTOM.

Q. TURN DRILL STRING 6 TURNS TO RIGHT TO DIS- ENGAGE RUNNING TOOL.

R. AS SOON AS RELEASE HAS BEEN ACCOM- PLISHED, AND WITH DIVERTER STILLCLOSED, CIR- C ULATE THROUGH DRILL STRING TO WASH OUT EX- CESS CEMENTABOVE 20 INCH HOUSING.

S. OPEN DIVERTER AND PULL DRILL STRING TO SURFACE.

T. MAKE UP DIVERTER RETRIEVING TOOL ON DRILL STRING. 5 U. ATTACH TODIVERTER AND PULL TO SURFACE.

STAGE IV OPERATIONS FOR THE 13-% INCH CASING, IE,

10 DRILLING 17% INCH HOLE, RUNNING AND CEMENT- ING THE CASING STRING;WILL BE HANDLED THROUGH A 20 INCH BLOWOUT PREvENTER STACK 62 CONSISTINGOF HYDRIL PREvENTER, PIPE RAMS 66, CHOKE AND KILL LINE CONNECTIONS 68,ETC.

A. THE 20 INCH 2,000 BLOWOUT PREvENTER STACK WITH 20 INCH CONNECTOR 70ON BOTTOM, IS SWUNG INTO PLACE UNDER THE ROTARY. STRING GUIDE LINESTHROUGH GUIDE FUNNELS AROUND STACK.

20 B. MAKE UP DRILL STRING ADAPTER TO TOP OF UPPER COLLET CONNECTOR 72WITH ENOUGH TAIL- PIPE T EXTEND THROUGH DRILL PIPE RAMS AND LOWERCONNECTOR.

C. INSTALL HYDRAULIC CONTROL LINES TO PREvENTER STACK AND CONNECTSEPARATE HOSES TO LOCK AND UNLOCK THE UPPER COLLET CONNECTOR.

D. ATTACH THE UPPER COLLET CONNECTOR TO PREvENTER STACK AND LOCK WITH1,500 PSI AND CLOSE RAMS ON DRILL STRING TAIL PIPE.

E. STRING GUIDE LINES THROUGH GUIDE FUNNELS ON PREvENTER STACK.

F. LOWER BLOWOUT PREvENTER STACK WITH DRILL STRING WHILE SLACKING OFF ONHYDRAULIC LINES.

G. LAND CONNECTOR AND BLOWOUT PREvENTER STACK ON 20 INCH HOUSING.

H. LOCK CONNECTOR WITH 1,500 PSI AND TEST LOWER CONNECTOR AND PIPE RAMSWITH PRES- SURE DOWN DRILL STRING. TEST PRESSURE SHOULD BE GOvERNED BYBURST ON 20 INCH CASING STRING.

I. RELEASE PRESSURE, OPEN RAMS, UNLOCK UPPER CONNECTOR AND PULLCONNECTOR AND DRILL STRING ADAPTER TO SURFACE.

J. MAKE UP BALL JOINT ON CONNECTOR AND STRING GUIDE LINES THROUGH GUIDEFUNNEL ON CONNECTOR.

50 K. MAKE UP CONNECTOR AND BALL JOINT ON RISER PIPE AND HAvE SEPARATEHYDRAULIC LINES ATTACHED TO UPPER CONNECTOR.

L. INSTALL CHOKE AND KILL LINE GUIDE FUNNELS ON RISER PIPE AS IT IS RUN.MAKE UP SLIP JOINT ON TOP OF RISER PIPE.

M. LAND AND LOCK CONNECTOR WITH 1,500 PSI ON TOP OF BLOWOUT PREvENTERSTACK.

N. SUSPEND TOP OF SLIP JOINT IN SLINGS.

O. RUN CHOKE AND KILL LINES THROUGH GUIDE FUNNELS ON RISER.

P. STAB AND MAKE UP CHOKE AND KILL LINES INTO CONNECTORS IN PREvENTERSTACK 62.

O. HANG OFF CHOKE AND KILL LINES ON SLIP JOINT AND CONNECT TO MANIFOLD.

R. DRILL l7-%INCI-I HOLE 74.

STAGE V A. RUN 13-%INCH CASING 76 (FIG. 5); INSTALL I3- %INCH HOUSING 78WHEN POINT IS REACHED.

B. MAKE UP RUNNING TOOL ON DRILL STRING AND ATTACH TO HOUSING BY TURNINGSIX TURNS TO LEFT.

C. ATTACH GUIDE FRAME, WITH ADAPTER FOR 13- INCH CASING, TO GUIDE LINES.

D. LOWER 13-% INCH CASING WITH RUNNING STRING TO ITS SEAT IN THE 20 INCHHOUSING. CE- MENT CASING STRING, WITH RETURNS COMING TO SURFACE.

E. WHEN PRESSURE CAN BE RELEASED, TURN RUNNING STRING TO RIGHT SIX TURNSTO DISEN- GAGE RUNNING TOOL. CIRCULATE, PULL DRILL STRING.

F. RELEASE LOWER COLLET CONNECTOR WITH 1,500 PSI AND PULL RISER SYSTEM,BLOWOUT PREVENTER STACK AND CONNECTOR.

EMERGENCY OPERATION IF 13-% INCH CASING SHOULD BECOME STUCK BE- FORE ITCAN BE LANDED IN THE 20 INCH HOUSING, USE FOLLOWING PROCEDURE.

A. PULL PRIMARY CEMENT JOB. LET SET.

B. TAKE STRAIN ON 13-% INCH CASING AND MEA- SURE STRETCH.

C. MEASURE A JOINT OF CASING TO BE RUN BETWEEN BROWN OIL TOOL CASINGPATCH TOOL AND 13% INCH HANGER.

D. RUN AN INSIDE 13-% INCH CASING CUTTER ON DRILL PIPE.

E. SPACE OUT TO CUT THE 13-% INCH CASING 2' BELOW THE HANGING SEAT OFTHE 20 INCH HOUS- ING, PLUS THE LENGTH OF THE JOINT MEASURED IN STEP E,AND LESS THE STRETCH MEASURED IN STEP B AND LESS LENGTH OF BROWN PATCHTOOL.

F. CUT AND REMOVE 13% INCH CASING.

G. MAKE UP BROWN CASING PATCH TOOL ON BOT- TOM OF JOINT OF CASINGMEASURED IN STEP C AND MAKE UP I3-% INCH HOUSING ON TOP OF THE JOINT.

H. MAKE UP RUNNING TOOL ON RUNNING STRING AND ATTACH TO 13-% INCHHOUSING.

I. LOWER CASING PATCH TOOL OVER 13-% INCH FISH AND LAND 13-% INCHHOUSING IN 20 INCH HOUSING.

J. RETRIEVE RUNNING TOOL AND MAKE UP CAS- ING SPEAR ON DRILL PIPE.

K. RUN IN HOLE AND LATCH IN CASING FISH.

L. PULL UP ON SPEAR TO PROPER WEIGHT TO SET CASING PATCH PACK OFF.

M. SLACK OFF ON DRILL PIPE; RELEASE AND RETRIEVE SPEAR.

N. TEST CASING AND PATCH TO DESIRED TEST PRESSURE OF 13-% INCH CASINGSTRING.

O. RETRIEVE RUNNING STRING AND RESUME NOR- MAL OPERATIONS. AT THISPOINT, WE GO TO A 5,000# MSP B.O.P. STACK 80 (FIG.- 5) FOR REMAININGOPERA- TIONS, I.E., DRILLING 12% INCH HOLE, RUNNING 9-% INCH CASING:DRILLING 8- /2 INCH HOLE, RUNNING 7 INCH CASING AND THE TUBING.

STAGE VI PICK UP AND SWING THE 13-% !INCH 5,000 PSI B.O.P. STACK 80BENEATH THE ROTARY. THE STACK WILL CONSIST OF AT LEAST FOUR SETS OF RAMTYPE 82 AND ONE BAG TYPE 84 PREVENTER, AS WELL AS THE LOWER COLLETCONNECTOR 86 AND THE CHOKE AND KILL LINE MANIFOLD.

A. MAKE UP COLLET CONNECTOR ADAPTER IN RUNNING STRING WITH TAIL PIPEEXTENDING BELOW ADAPTER.

B. ATTACH ADAPTER TO TOP CONNECTOR WITH TAIL PIPE EXTENDING THROUGHCONNECTOR AND BOP STACK.

C. INSTALL HYDRAULIC CONTROL LINES 88 TO PREVENTER STACK WITH SEPARATEHOSES CON- NECTED TO LOCK AND UNLOCK PORTS ON UPPER COLLET CONNECTOR.

D. LOCK THE COLLET CONNECTOR TO THE HUB ON PREVENTER STACK WITH 1,500PSI AND CLOSE PIPE RAMS ON DRILL PIPE STINGER.

E. STRING GUIDE LINES 60 THROUGH GUIDE FUN- NELS 90 AND UPPER COLLETCONNECTOR.

F. LOWER BOP STACK ON DRILL PIPE WHILE SLACKING OFF HYDRAULIC LINES.

G. LAND CONNECTOR AND BOP STACK ON 13-% INCH HOUSING.

H. LOCK LOWER COLLET CONNECTOR WITH 1,500 PSI THEN TEST LOWER CONNECTORAND PREVEN- TERS WITH DESIRED PRESSURE DOWN DRILL PIPE.

I. RELEASE PRESSURE, OPEN DRILL PIPE RAMS, UN- LOCK UPPER CONNECTOR ANDPULL DRILL STRING AND CONNECTOR TO SURFACE.

J. MAKE UP 13-% INCH COLLET CONNECTOR AND 13-% INCH BALL JOINT.

K. STRING GUIDE LINES THROUGH GUIDE F UNNELS ON CONNECTOR AND BALLJOINT.

L. MAKE UP AND RUN COLLET CONNECTOR AND BALL JOINT ON RISER PIPE 92 WITHSEPARATE HYDRAULIC LINES CONNECTED TO UPPER COLLET CONNECTOR.

M. INSTALL CHOKE AND KILL GUIDE FUNNELS ON RISER PIPE AS IT IS RUN.

N. MAKE UP SLIP JOINT ON TOP OF RISER PIPE.

0. LAND AND LOCK CONNECTOR WITH 1,500 PSI ONTO HUB OF PREVENTER STACK.

P. SUSPEND TOP OF SLIP JOINT IN SLINGS.

Q. RUN CHOKE AND KILL LINES THROUGH GUIDE FUNNELS ON RISER.

R. STAB AND MAKE UP CHOKE AND KILL LINES INTO CONNECTORS ON PREVENTERSTACK.

S. HANG OFF CHOKE AND KILL LINES ON SLIP JOINT AND TIE TO MANIFOLD.PREPARING TO DRILL 12-% INCH HOLE AND RUN 9-% INCH CASING A. MAKE UPTEST PLUG ON DRILL STRING AND LOWER TO SEAT IN 13-% INCH HOUSING.

B. CLOSE PIPE RAMS ON DRILL PIPE AND TEST PREVENTERS AND CONNECTOR TO5,000 PSI DOWN THE KILL LINE.

C. RELEASE PRESSURE, OPEN RAMS, RETRIEVE TEST PLUG.

D. INSTALL 12 INCH WEAR SLEEVE RUNNING TOOL ON DRILL PIPE.

E. MAKE UP RUNNING TOOL IN 12 INCH WEAR SLEEVE WITH FOUR TURNS TO RIGHTBUT DO NOT TIGHTEN.

F. LOWER AND LAND WEAR SLEEVE IN 13-% INCH HOUSING.

G. DISENGAGE RUNNING TOOL FROM WEAR SLEEVE WITH FOUR TURNS TO LEFT;RETRIEVE RUNNING TOOL AND DRILL STRING.

H. DRILL 12-/4 INCH HOLE.

I. BEFORE RUNNING 9-% INCH CASING 94, MAKE UP WEAR SLEEVE RUNNING TOOLON DRILL PIPE.

J. RETRIEVE WEAR SLEEVE BY TURNING DRILL PIPE FOUR TURNS TO RIGHT.

K. PULL WEAR SLEEVE TO SURFACE.

STAGE VII A. RUN 9-% INCH CASING; MAKING UP SEAL AS- SEMBLY AND 9-% INCHHOUSING WHEN SETTING DEPTH IS REACHED.

B. MAKE UP RUNNING TOOL ON CASING LANDING STRING.

C. ATTACH RUNNING TOOL TO 9-% INCH HOUSING AND SEALING DEVICE WITH EIGHTTURNS TO RIGHT.

D. LOWER AND LAND 9-% INCH CASING HOUSING 96 IN I3-% INCH HOUSING ANDCEMENT.

E. WHEN PRESSURE CAN BE RELEASED, TURN LANDING STRING I0 TURNS TO RIGHT.THIS WILL AC- TUATE PACKING BETWEEN THE 133$ INCH X 9-% INCH ANNULUS.

F. CONTINUED RIGHT HAND ROTATION WILL DIS- ENGAGE SEALING DEVICE FROM9-% INCH HOUSING.

G. CLOSE RAMS ON CASING LANDING STRING AND TEST TO REQUIRED PRESSURE ON9-% INCH CASING.

H. RELEASE PRESSURE, OPEN RAMS AND PULL LANDING STRING AND TOOLS TOSURFACE.

PREPARE TO DRILL 8-V2 INCH HOLE AND RUN 7 INCH CASING A. INSTALL INCHWEAR SLEEVE RUNNING TOOL ON RUNNING STRING.

B. MAKE UP RUNNING TOOL IN 10 INCH WEAR SLEEVE WITH FOUR TURNS TO RIGHTBUT DO NOT TIGHTEN.

C. LOWER AND LAND WEAR SLEEVE IN 9-% INCH HOUSING.

D. DISENGAGE RUNNING TOOL FROM WEAR SLEEVE BY TURNING FOUR TURNS TOLEFI'. RETRIEVE RUNNING TOOL AND DRILL STRING.

E. DRILL 8% INCH HOLE.

F. BEFORE RUNNING 7 INCH CASING 98, MAKE UP WEAR SLEEVE RUNNING TOOL ONDRILL STRING.

G. RETRIEVE WEAR SLEEVE BY TURNING FOUR TURNS TO RIGHT AND PULL TOSURFACE.

STAGE VIII A. RUN 7 INCH CASING 98, MAKING UP SEAL AS- SEMBLY AND 7 INCHHOUSING WHEN SETTING DEPTH IS REACHED.

B. MAKE UP RUNNING TOOL ON CASING LANDING STRING.

C. ATTACH RUNNING TOOL TO 7 INCH HOUSING AND SEALING DEVICE WITH EIGHTTURNS TO RIGHT.

D. LOWER AND LAND 7 INCH CASING HOUSING IN 9-% INCH HOUSING AND CEMENT.

E. WHEN PRESSURE CAN BE RELEASED, TURN LANDING STRING TO RIGHT. THISWILL ACTUATE PACKING BETWEEN THE 9-% INCH X 7 INCH ANNU- LUS.

F. CONTINUED RIGHT HAND ROTATION WILL DIS- ENGAGE SEALING DEVICE FROM9-% INCH HOUSING.

G. CLOSE RAMS ON CASING LANDING STRING AND TEST TO REQUIRED TESTPRESSURE ON 7 INCH CAS- ING.

H. RELEASE PRESSURE, OPEN RAMS AND PULL LANDING STRING AND TOOLS TOSURFACE.

WELL COMPLETION PROCEDURE One of the advantages of the wellheadhemisphere and work chamber concept is that the christmas tree or flowmanifold portion of the wellhead assembly can be less sophisticated thanthose usually associated with a sub-sea completion in deep water.

We offer a simple on land" type flow manifold that would have two mastervalves, crown valve, wing valve and choke. These components would haveactuators controlled from the control center on the storage vessel.

Since we will be set up for certain wire line operations within the workchamber, the T.F.L. loop and diverter could be omitted. By the sametoken, one string of tubing could be used for a single completion whiletwo strings could be reserved for dual completion.

It is realized that methods of completing a well do vary from operatorto operator and also from well to well; most of which are individual andmust be handled as such.

Let us then examine methods best suited for our sub-sea system:

A. PERFORATE AND TEST IN A GREAT NUMBER OF CASES, THE OPERATOR WILL WISHTO PERFORATE AND TEST THE PRODUC- ING HORIZON BEFORE GOING THROUGH THEAC- Ill TUAL COMPLETION SEQUENCE. THIS TEST WOULD CONFIRM THE INTEGRITYOF THE CEMENT JOB AND VERIFY EXPECTED FLOW CHARACTERISTICS OF THE OIL ORGAS BEARING SAND. IF BLOCK SQUEEZING MUST BE DONE, NOW WOULD BE THE BESTTIME FOR IT.

B. RUN PACKER WITH TUBING THE HYDROSET PACKER Is BEsT FOR THE TYPEOPERATION. WHEN SETTING DEPTH IS REACHED, THE TUBING HANGER, wHIcH HAs AsEcoND PoRT FOR CIRCULATING, IS MADE UP IN THE TUBING STRING.

c. THE TUBING Is LANDED WITH AN OTIS HYDRAU- LIC OPERATED DUAL vALvEATTACHED TO THE TUBING HANGER AND LANDING TOOL.

D. WITH HYDRAULIC PRESSURE ON THE BALL VALVES TO KEEP THEM oPEN, WEDISPLACE THE TUBING.

E. wHEN TUBING IS DIsPLAcED, THE SETTING BALL IS LANDED IN THE RECEIVERAND PRESSURE APPLIED TO THE TUBING To sET PACKER.

F. HYDRAULIC PRESSURE Is RELEASED To CLOSE BALL vALvEs.

G. PUMP DowN TUBING sTRING TO TEST BALL vALvEs.

H. RELEASE LANDING TOOL AND PULL RUNNING STRING.

TUBING GUN'PERFORATING METHOD IN THE EVENT THE OPERATOR WISHES TO PER-FORATE THE PRODUCING ZONE AFTER RUNNING TUBING AND SETTING PACKERS; THEPROCEDURE IS AS FOLLOWS:

A. RUN TUBING; PLACING HYDROSET PACKET TO FALL AT PROPER INTERVAL.

B. WHEN LANDING POINT IS REACHED, MAKE UP TUBING HANGER, OTIS HYDRAULICDUAL VALVES AND RUNNING TOOL.

C. LOWER TUBING HANGER TO ITS SEAT IN THE 7 INCH BOWL.

D. ACTUATE HYDRAULIC PRESSURE TO OPEN BALL VALVES.

E. DISPLACE TUBING, TAKING RETURNS THROUGH TUBING HANGER PORT AND INTORISER PIPE TO SUR- FACE.

F. LAND PACKER SETTING BALL IN RECEIVER AND APPLY PRESSURE TO TUBINGSTRING TO SET PACKER. I

G. RIG UP LUBRICATOR AT SURFACE ON EX- TENDED TUBING STRING TOACCOMMODATE PER- FORATING GUN.

H. LOWER GUN TO PROPER INTERVAL, PER- FORATE.

I. PULL GUN TO A POINT ABOVE HYDRAULIC BALL VALVES AT WELLHEAD.

J. RELEASE HYDRAULIC PRESSURE TO CLOSE BALL VALVES.

K. RETRIEVE GUN, RIG DOWN LUBRICATOR.

L. PUMP DOWN TUBING STRING TO TEST BALL VALVES.

M. RELEASE LANDING TOOL AND PULL LANDING STRING. THE WELL IS NOW READYFOR PRODUCTION BUT CLOSED IN WITH THE OTIS HYDRAULIC BALL VALVES. WE ARENOW READY TO DISMANTLE THE 13-% INCH B.O.P. STACK AND RELEASE THE DRILLSHIP (FIG. 6).

OPERATIONS CONTINUE AT THE WELLHEAD WHEN THE WORK CHAMBER (FIG. 7) HASBEEN LOWERED AND FASTENED TO THE HEMISPHERE 20 AND AN ATMOSPHERICCONDITION PREVAILS.

A. THE TUBING PLUGGING TOOL 102 (FIG. 10) IS RIGGED UP ON THE OTIS BALLVALVE ABOVE TUB- ING STRING.

B. A COVER PLUG MADE UP ON THE ANNULUS PORT OF BALL VALVE.

C. HYDRAULIC PRESSURE IS APPLIED TO OPEN BALL VALVES.

D. TUBING PLUG IS SET IN TUBING HANGER.

E. PLUGGING TOOL IS REMOVED TO ANNULUS PORT AND PROCEDURE CONTINUED TOSET BACK PRESSURE VALVE IN PLACE.

F. OTIS BALL VALVES REMOVED.

G. INSTALL PERMANENT WELLHEAD MASTER VALVE ASSEMBLY AND TEST CONNECTION.

H. REMOVE TUBING PLUGS THROUGH MASTER VALVES. WHEN FLOW LINES HAVE BEENIN- STALLED, MAKE CONNECTION TO CHOKE AS- SEMBLY. CONNECT MASTER VALVEAND CHOKE AC- TUATOR LINES FOR REMOTE CONTROL OF THE WELLHEAD ASSEMBLY.

Referring to FIG. 7, the well is shown completed to a point where theconductor bore has been drilled through drilling template and 26 inchcasing run with the guide base lower hemisphere 20 connected to and runwith the last joint of casing. The integrity of the connection seal istested prior to lowering. The lower hemisphere 20 contains a plurality,for instance, four standard guide posts 38 and latches plus a plurality,for instance, three to 12 flow line and access line connector mechanisms104 (FIG. 12).

As may be seen, cementing has been completed and the original drillingtemplate guide lines 18 (FIG. 1) have been removed.

The underwater work chamber 100 which has been pulled down from afloating bell tender using a self-contained wire line which is shownhaving made contact with the lower hemisphere, orienting itself on theguide posts. (Note that the guide lines have been removed prior tolowering the work chamber.) Also, all casing, tubing and hangers havebeen run set and/or cemented. Tubing plugs run with the tubing affordpressure protection while running and nipple up. In addition, the riserand B.O.P. stack have been removed during the stage of FIG. 6.

Guide lines may be lowered with the work chamber to facilitate theeventual installation of the flow and access lines.

Turning now to FIG. 10, the work chamber 100 has been positioned on thehemisphere and the inflatable seals 104, 106 have been actuated. Theentrapped water, having been displaced using a suction pump on the workchamber having an inlet hose which protrudes below the floor of the workchamber to adjacent the bottom of the hemispherical member, the workarea being the space below the floor and within the hemisphere, ischarged with one atmosphere of a breathable gas mixture.

Note that the hydraulic cylinders 108 (FIG. 11) serve as positionlatches between the work chamber and the lower sphere.

FIG. depicts the completion of the installation of the production treewith the upper portion of the flow loop 110.

The flow lines and manifold have been lowered on the guide cablesoutside the chamber into their clevis and a standard tubing pluggingtool 102 has been attached to the gate valve 114. This is preparatory tothe actuation of the flow line bridge sleeve 118 and to remove the flowline tubing plugs.

After rotating the bridge sleeve into place and testing the seals, thetubing plugs may be removed. It remains only to install the missingsegment (dashed line 120, FIG. 10) of flow loop 110.

In FIG. 10, the 3% inch 9.3 plug 102 installed at the surface serves toprevent entrance of sea water while the Gray Gate Valve 114 (orequivalent) is installed by the crew.

The 2% inch 6.5 plug lowered in place, with the flow line, prevents theentrance of sea water into the flow line and later serves as a test plugfor the bridge sleeve.

Upon opening the gate valve 114, a special tool with a collapsible keyarrangement is pushed through the valve to engage and screw the bridgingsleeve into place. The linear motion is achieved through a system ofscrew threads contained in the plug tool and is operated by rotaryeffort applied to the crank.

After the bridging sleeve is screwed into place and the hydraulicpacking seal is tested, the collapsible keyed tool 102 is withdrawn andthe gate valve closed.

The placement of the bridging sleeve 118 serves a twofold purpose: (1)to effect a positive seal between the flow line manifold and the flow'line connector; (2) although the bridging sleeve is illustrated as beingactuated mechanically through the use of a thread system, a hydraulicpiston system could be utilized, eliminating the need for the threads.The nose 122 of the bridging sleeve also provides a structural linkbetween flow line and connector, preventing accidental vertical motionbetween flow line and flow line connector.

Completing the setting and testing of the bridge sleeve, the collapsiblekey tool is removed and replaced by a plug retrieving tool which ispushed through the gate valve whereupon it contacts, seizes and unscrewsthe 3% inch 9.3 it plug.

Having removed the 3% inch 9.3 i plug, the plug tool and retrievingattachment may next be employed for the removal of the 2% inch 6.5 plug,following which the flow line itself may be tested.

As a quantity of these flow line connectors and landing clevises may beinstalled in the wall of the receptacle, the orientation of thereceptacle 20 as it is landed on the ocean floor is of small concern;i.e., a flow line(s) 116 may be attached and dispersed in virtually anydirection.

As an added safety feature, a plastic injection seal system is providedon each flow line connector and should a leak occur in the CWC typeseal, a quantity of a viscous plastic preparation may be injected intothe seal areas.

Subsequent to the stage depicted in FIG. 10, the flow system may becompleted and wire line lubricator may be assembled atop the productiontree with which tubing plugs may be removed and divertors installed. Anyother wire line operations may be performed.

A contamination separator may be placed immediately 0 above the wireline B.O.P.s to prevent undesirable hydrocarbons from entering the workarea during wire line operations.

After the well has been completed and turned into the gathering system,the crew may return to the personnel quarters 130 in the upper end ofthe chamber 100 above its floor and the floor hatch closed 132. Thepressure in the work area 134 is then allowed to equalize with outsidehydrostatic pressures, and the hold-down latches 108 are released, thuspermitting the work chamber to surface.

The pictorial view in FIG. 12 shows the work chamber 100 as it wouldappear leaving a new well site or returning to work over an old one.

The two inflatable seals 104, 106 provided in accordance with theinvention preferably consist of identical assemblies welded to theexterior of the work chamber near its lower exterior. The sealassemblies are slightly axially spaced from one another to provide fortest and hydraulic supply ports (FIG. 11) between them, through thepermanent, lower and submersible upper members side walls as shown inFIG. 11.

The two inflatable seal assemblies each include a tubular plate 142 towhich two axially spaced seal confining elements 144 are welded. Eachseal consists of a tubular rubber inner member 146, an intennediatetubular layer of overlapping steel braids 148 and an outer covering ofrubber 150.

Each seal assembly 104, 106, although much larger in size, for instance,being 16 feet in outer diameter when uninflated, is of the same materialas the rubbers of the packers shown on pages 3,00l3,020, and especiallyon pages 3,002 and 3,015, of the Composite Catalog of Oil FieldEquipment and Services, 1968-1969 Edition, Gulf Publishing Company,Houston, Texas. At this size, the radial clearance between the sealswhen uninflated and the inner peripheral surface of the lowerhemispherical member 20 is, for instance, 1% inches.

Lines 152 for inflating the seals may be connected to hydraulic pressurepumps within the work chamber.

It should now be apparent that the underwater completion system asdescribed hereinabove possesses each of the attributes set forth in thespecification under the heading Summary of the Invention hereinbefore.Because the underwater completion system of the invention can bemodified to some extent without departing from the principles of theinvention as they have been outlined and explained in thisspecification, the present invention should be understood and acceptedas encompassing all such modifications as are within the spirit andscope of the following claims.

What is claimed is:

1. An underwater well completion system including:

a lower upwardly opening hemispherical shell base permanently mounted onan underwater well so as to surround the wellhead adjacent theunderwater bottom;

a plurality of angularly spaced flow line connectors protruding throughthe hemispherical shell base;

a submersible work chamber having a lower end receivable into the upperend of the hemispherical shell base with substantial clearance;

at least two axially spaced inflatable seal assemblies exteriorlymounted on said submersible work chamber near said lower end to bereceived into said hemispherical shell base;

opening means through said submersible work chamber into each saidinflatable seal assembly for inflating each into circumferential sealingcontact with said hemispherical shell base;

at least one upwardly protruding guide post on said hemispherical shellbase; at least one guide sleeve on said submersible work chamber adaptedto slide down over said guide post; means defining a detent in saidguide post and means defining a latch on said submersible work chamber,actuable to enter said detent means to lock said submersible work saidhemispherical shell base.

2. An underwater well completion system including:

a lower upwardly opening hemispherical shell base permanently mounted onan underwater well so as to surround the wellhead adjacent theunderwater bottom;

a plurality of angularly spaced flow line connectors protruding throughthe hemispherical shell base;

a submersible work chamber having a lower end receivable into the upperend of the hemispherical shell base with substantial clearance;

at least two axially spaced inflatable seal assemblies exteriorlymounted on said submersible work chamber near said lower end to bereceived into said hemispherical shell base; 7

opening means through said submersible work chamber into each saidinflatable seal assembly for inflating each into circumferential sealingcontact with said hemispherical shell base; port means through saidhemispherical shell base between the locations of said inflatable sealsfor providing access to the region between said seals for pressuretesting and fluid removal.

3. An underwater well completion system including:

a lower upwardly opening hemispherical shell base permanently mounted onan underwater well so as to surround the wellhead adjacent theunderwater bottom;

a plurality of angularly spaced flow line connectors protruding throughthe hemispherical shell base;

a submersible work chamber having a lower end receivable into the upperend of the hemispherical shell base with.

substantial clearance;

at least two axially spaced inflatable seal assemblies exteriorlymounted on said submersible work chamber near said lower end to bereceived into said hemispherical shell base;

' opening means through said submersible work chamber into each saidinflatable seal assembly for inflating each into circumferential sealingcontact with said hemispherical shell base; each seal assemblyll'lClUdll'lg a tubular stationary base provided at each axial end witha stationary seal confining element, and a tubular seal received betweensaid confining elements and comprising an inner layer of flexiblerubber, an intermediate layer of overlapped steel braiding and an outerlayer of rubber; and means defining a seal inflation port through eachtubular steel base.

1. An underwater well completion system including: a lower upwardlyopening hemispherical shell base permanently mounted on an underwaterwell so as to surround the wellhead adjacent the underwater bottom; aplurality of angularly spaced flow line connectors protruding throughthe hemispherical shell base; a submersible work chamber having a lowerend receivable into the upper end of the hemispherical shell base withsubstantial clearance; at least two axially spaced inflatable sealassemblies exteriorly mounted on said submersible work chamber near saidlower end to be received into said hemispherical shell base; openingmeans through said submersible work chamber into each said inflatableseal assembly for inflating each into circumferential sealing contactwith said hemispherical shell base; at least one upwardly protrudingguide post on said hemispherical shell base; at least one guide sleeveon said submersible work chamber adapted to slide down over said guidepost; means defining a detent in said guide post and means defining alatch on said submersible work chamber, actuable to enter said detentmeans to lock said submersible work chamber to said hemispherical shellbase.
 2. An underwater well completion system including: a lowerupwardly opening hemispherical shell base permanently mounted on anunderwater well so as to surround the wellhead adjacent the underwaterbottom; a plurality of angularly spaced flow line connectors protrudingthrough the hemispherical shell base; a submersible work chamber havinga lower end receivable into the upper end of the hemispherical shellbase with substantial clearance; at least two axially spaced inflatableseal assemblies exteriorly mounted on said submersible work chamber nearsaid lower end to be received into said hemispherical shell base;opening means through said submersible work chamber into each saidinflatable seal assembly for inflating each into circumferential sealingcontact with said hemispherical shell base; porT means through saidhemispherical shell base between the locations of said inflatable sealsfor providing access to the region between said seals for pressuretesting and fluid removal.
 3. An underwater well completion systemincluding: a lower upwardly opening hemispherical shell base permanentlymounted on an underwater well so as to surround the wellhead adjacentthe underwater bottom; a plurality of angularly spaced flow lineconnectors protruding through the hemispherical shell base; asubmersible work chamber having a lower end receivable into the upperend of the hemispherical shell base with substantial clearance; at leasttwo axially spaced inflatable seal assemblies exteriorly mounted on saidsubmersible work chamber near said lower end to be received into saidhemispherical shell base; opening means through said submersible workchamber into each said inflatable seal assembly for inflating each intocircumferential sealing contact with said hemispherical shell base; eachseal assembly including a tubular stationary base provided at each axialend with a stationary seal confining element, and a tubular sealreceived between said confining elements and comprising an inner layerof flexible rubber, an intermediate layer of overlapped steel braidingand an outer layer of rubber; and means defining a seal inflation portthrough each tubular steel base.